Hose with releasable float for leak detection

ABSTRACT

An object of the present invention is to provide a hose of low cost, which can be installed very easily, which remains reliable over a long period of time, and in which damage to the inner construction can be easily discovered. An auxiliary pressure cord layer 7 is capable of being deformed by the pressure of a fluid in a chamber 9. A float 10 attached to a hose 1 with a mooring line is also attached to a hose body 2 through a connecting member, and when an amount of deformation of the auxiliary pressure cord layer 7 has reached a predetermined value, the connecting member is fractured and the float 10 is separated from the hose 1.

TECHNICAL FIELD

The present invention relates to a hose for transporting a fluid such asoil or the like in the sea or in the water, and more particularlyrelates to a hose in which damage to a pressure cord layer can be easilyfound even when it is used in the sea or in the water.

BACKGROUND ART

Conventionally, a hose line composed of a plurality of hoses connectedend-to-end is used for loading a tanker with oil or the like, orunloading the tanker, because the tanker is generally moored offshore.

In the case where a hose used for the hose line is damaged in anemergency, oil leaks out from the hose line, and serious environmentalpollution results. Therefore, the hose used for the hose line has adouble construction in which an auxiliary pressure cord layer isprovided outside the main pressure cord layer which provides a chamberinto which fluid that has leaked through the main pressure layer flows.In the case where the main pressure cord layer is damaged, the fluidthat leaks out from the main pressure cord layer is retained in thechamber enclosed by the auxiliary pressure cord layer. Accordingly, inthe prior art, if the outer appearance of the hose is visually inspectedto be changed, the damage in the hose is determined.

In this connection, when the hose is used in the sea, it is impossibleto determine the occurrence of damage visually. Therefore, a detector isprovided in the hose, by which a change in pressure of the fluid thathas leaked out from the main pressure cord layer into the chamber isdetected, and a signal sent from the detector is received by a receiverinstalled on the sea or ground, so that the occurrence of damage of themain pressure cord layer is determined.

When the hose is used in the sea as described above, it is necessary toprovide auxiliary apparatus such as a detector and receiver. Therefore,the installation of the hose is complicated, and the cost of the hose isgreatly increased.

Furthermore, the detector tends to be damaged and malfunctions tend tooccur, so that the aforementioned detection system lacks reliabilitywhen it is used over a long period of time.

DISCLOSURE OF THE INVENTION

The present invention has been made in view of the foregoing problems ofthe prior art. It is therefore an object of the present invention toprovide a hose characterized in that: installation of the hose is veryeasy; the cost is low; the reliability is high even if it is used over along period of time; and damage in the hose can be easily detected.

In order to accomplish the above objects, the present invention providesa hose comprising: a main pressure cord layer for retaining andcirculating a fluid; an auxiliary pressure cord layer sheathing the mainpressure cord layer; and a chamber for retaining the fluid leaking fromthe main pressure cord layer, said chamber being formed between the mainpressure cord layer and the auxiliary pressure cord layer, wherein theauxiliary pressure cord layer is capable of being deformed by thepressure of the fluid retained in the chamber, the hose furthercomprising a float moored on the hose, the float being connected to thehose through a connection member, wherein the connection member isfractured and the float is released from the hose when an amount ofdeformation of the auxiliary pressure cord layer has increased to apredetermined value.

The present invention is constructed in the manner described above whenthe main pressure cord layer is damaged and the transported fluid flowsinto the chamber, the auxiliary pressure cord layer is deformed by thefluid pressure. When an amount of deformation of the auxiliary pressurecord layer is increased to a predetermined value, the connecting memberis fractured, so that the float is released from the hose and floats inthe sea, Since the float is moored at the hose, it does not flow awaybut floats around the hose, the main pressure cord of which has beendamaged. Consequently, when the floating float is discovered, it ispossible to find the hose, the main pressure cord layer of which hasbeen damaged.

According to a preferred embodiment of the present invention, an annularfloat mount is integrally attached to the hose, and a plurality offloats divided into pieces in the circumferential direction are disposedadjacent to the annular float mount. Also, each float is moored at thehose with a mooring rope accommodated in the float mount.

As an embodiment of the present invention, the auxiliary pressure cordlayer is composed in such a manner that it is mainly deformed in thelongitudinal direction of the hose by the action of pressure of thefluid retained in the chamber, a pair of float mounts are integrallyattached to the hose at an interval in the longitudinal direction, thefloats are respectively disposed on the hose end sides of the floatmounts, these floats are connected by wires penetrating through thefloat mounts, and the floats are released from the hose when an amountof longitudinal deformation of the auxiliary pressure cord layer hasincreased to a predetermined value. In this case, it is preferable thatthe floats are connected to the wires through fuse washers which arefractured when a predetermined stress is applied.

According to another embodiment of the present invention, the auxiliarypressure cord layer is composed in such a manner that it is mainlyexpanded and deformed in the radial direction of the hose by the actionof pressure retained in the chamber, the float mount is integrallyattached to the hose, the float moored at and disposed adjacent to thefloat mount is fastened and fixed to the hose by an annular floatfastening fixture, and the float is released from the hose when anamount of expanding deformation in the radial direction of the auxiliarypressure cord layer has increased to a predetermined value. In thiscase, the annular float fixture is preferably fastened and fixed to thehose through a bolt and nut, with a fuse washer which is fractured whena predetermined stress is applied.

According to still another embodiment of the present invention, theauxiliary pressure cord layer is composed in such a manner that it ismainly deformed in a twisting direction by the action of pressure of thefluid retained in the chamber, a pair of float mounts are integrallyattached to the hose at an interval in the longitudinal direction,floats are disposed between these float mounts, and the floats arerespectively connected to the float mounts through a fuse bolt which isfractured when a predetermined stress is applied. In this case, it ispreferable that the float is annular and divided into a plurality ofpieces in the circumferential direction, and the pieces of the dividedfloat are alternately connected to one or the other of the pair of floatmounts by the fuse bolts.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view showing the first embodiment of the hose of thepresent invention.

FIG. 2 is a sectional view of an end portion of the hose showing theconstruction of the hose illustrated in FIG. 1.

FIG. 3 is a schematic illustration for explaining the orientation ofcords of the main pressure cord layer shown in FIG. 2.

FIG. 4 is a schematic illustration for explaining the orientation ofcords of the auxiliary pressure cord layer shown in FIG. 2.

FIG. 5 is an enlarged sectional view of the V portion shown in FIG. 1.

FIG. 6 is a sectional view showing a mounting condition of a floatdivided into three pieces.

FIG. 7 is a partially sectional front view showing a portion of the hoseof the second embodiment of the present invention.

FIG. 8 is a schematic illustration showing a condition in which thefloat is mounted in the second embodiment shown in FIG. 7.

FIG. 9 is a front view showing a portion of the hose of the thirdembodiment of the present invention.

FIG. 10 is a schematic illustration for explaining the orientation ofthe auxiliary pressure cord layer of the third embodiment shown in FIG.9.

FIG. 11A is a sectional view taken on line A--A in FIG. 9.

FIG. 11B is an enlarged sectional view of the portion B in FIG. 9.

FIG. 12 is a schematic illustration showing a twist of the hose body inFIG. 9.

FIG. 13 is a schematic illustration of an asymmetrical cord layer onwhich a cord arrangement of the cord layer is formed approximatelysymmetrical with respect to the transverse direction at the center ofthe hose.

FIG. 14 is a schematic illustration showing a twist of the hose having acord layer shown in FIG. 13.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to the accompanying drawings, an embodiment of thepresent invention will be explained as follows.

FIG. 1 shows the first embodiment of the present invention. The hose 1is approximately 9 m to 12 m long. Although not shown in the drawing, alarge number of hoses 1 are connected in use. Each hose 1 includes: ahose body 2 capable of being deformed when the inner construction isdamaged; flanges 3 for connecting the hoses 1, the flanges 3 beingprovided on both sides of the hose body 2; and floats 10 capable ofbeing released from the hose 1 when the inner construction of the hose 1is damaged, the floats 10 being provided on the outer circumferences ofboth ends of the hose body 2.

As illustrated in the sectional view of FIG. 2, the hose body 2 iscomposed of: a rubber tube layer 4 made of acrylonitrile-butadienerubber (ANBR) which is provided inside most; a main pressure cord layer5 for holding the fluid, such as oil, transported in the hose 1, whereinthe main pressure cord layer 5 covers the rubber tube layer 4; and anauxiliary pressure cord layer 7 capable of holding a fluid which hasleaked from the rubber tube layer 4 and the main pressure cord layer 5,the auxiliary pressure cord layer 7 being provided outside the mainpressure cord layer 5 through an intermediate rubber layer 6 made of NBRor the like. On the auxiliary pressure cord layer 7, there is provided acover rubber layer 8 made of styrene-butadiene rubber (SBR) so that thehose body 2 is covered.

Between the main pressure cord layer 5 and the intermediate rubber layer6 adhered onto the auxiliary pressure cord layer 7, there is provided achamber 9 having a liquid-tight property, and a fluid that has leakedout from the rubber tube layer 4 and the main pressure cord layer 5flows into and remains in the chamber 8. This chamber 9 is a spaceformed between the main pressure cord layer 5 and the intermediaterubber layer 6. Alternatively, the main pressure cord layer 5 and theintermediate rubber layer 6 are adhered to each other, and they areseparated by the pressure of a fluid that has leaked out from the rubbertube layer 4 and the main pressure cord layer 5, so that a space can beformed when the leaking fluid flows between the main pressure cord layer5 and the intermediate rubber layer 6 and the two layers are separated.

As shown in FIG. 3, the main pressure cord layer 5 is composed of cordplies each formed by helically winding cords f, produced by twistingnylon strands, polyester strands, rayon strands, aromatic polyamidestrands or steel wires, and coating each ply of the cords f with SBR orthe like. The cord plies of the cords f include one or more first cordply each composed of the cords f extending in one helical direction at ahelix angle θ₁, and a second cord ply each composed of the cords f inthe opposite helical direction at the same helix angle θ₁, but thenumber of cords in the first cord ply is equal to that in the secondcord ply.

The helix angle θ₁ is in a range defined by 30°<θ₁ <60°, morepreferably, in a range defined by 35°<θ₁ ≦55°. The helix angle θ below30° deteriorates the flexibility of hose body 2 and the helix angle θ₁greater than 60° makes the hose body 2 excessively flexible, which makesthe hose 1 difficult to handle. A helix angle θ₁ greater than 35° andnot greater than 55° enables the cord plies to impart flexibility to thehose body 2 and efficiently enhances the pressure-withstanding strengthof the hose body 2. Unlike the auxiliary pressure cord layer 7 describedlater, the number of layers (the number of plies) in the main pressurecord layer 5 is larger than that in the auxiliary pressure cord layer 7so that the main pressure cord layer 5 can not be easily deformed by thepressure of fluid in the hose.

The auxiliary pressure cord layer 7 is constructed in such a manner thatit is extended in the longitudinal direction of the hose body 2 by thepressure of fluid when the fluid has leaked out from the rubber tubelayer 4 and the main pressure cord layer 5. As shown in FIG. 4, theauxiliary pressure cord layer 7 is composed of cord plies each formed byhelically winding cords c, produced by twisting nylon strands, polyesterstrands, rayon strands, aromatic polyamide strands or steel wires, andcoating each cord ply of the cords c with SBR or the like. The cordplies of the cords c include one or more first cord ply each composed ofthe cords c extending in one helical direction at a helix angle θ₂, andsecond cord plies each composed of the cords c in the opposite helicaldirection at the same helix angle θ₂. The number cords in the first cordply is equal to that in the second cord ply.

The helix angle θ₂ is in a range of 54°<θ₂ <90° with respect to thelongitudinal direction of the hose body 2. In the case where θ₂ is notmore than 54°, a sufficient elongation can not be expected with respectto the longitudinal direction of the hose body 2. It is preferable thatthe angle θ₂ is in a range of 65°<80°. When the helix angle θ₂ of thecord c of the auxiliary pressure cord layer 7 is relatively large, theauxiliary pressure cord layer 7 can be easily elongated in thelongitudinal direction by the pressure of fluid when the fluid hasleaked out from the rubber tube layer 4 and the main pressure cord layer5.

It is preferable that the chamber 9 is packed with a buffering membersuch as a sponge having open voids or closed voids. When a pressurebuffering layer, composed of the buffering member described above, is inthe chamber 9, the pressure of leaking fluid can be absorbed when therubber tube layer 4 and the main pressure cord layer 5 have beendamaged, so that a shock applied to the intermediate rubber layer 6 canbe reduced, and the auxiliary pressure cord layer 7 is not damaged.

A ring portion 3b for attaching the hose body 2 is integrally providedon an outer circumferential surface of the cylinder portion 3a of theflange 3. The hose body 2 and the flange 3 are connected and joined inthe following manner:

An end portion of the hose body 2 is fixed to the ring portion 3b byfastening wires 5a, 7a provided at the ends of the main pressure cordlayer 5 and the auxiliary pressure cord layer 7, and the end portions ofthe layers composing the hose body 2 are adhered to each other.

As illustrated in FIGS. 1 and 5, the floats 10 are attached onto theouter sides of annular float mounts 11a, 11b integrally formed on theouter circumferences of both ends of the covering rubber layer 8. Inthis case, the floats 10 are attached through the following connectingmembers: a wire 12 extending between both float mounts 11a and 11b, bothends of the wire 12 being provided with male screw portions; a fusewasher 13 inserted into the male screw portion; and a nut screwed to themale screw portion. In order to prevent the floats 10 from flowing awayfrom the hose body 2 in the case where the fuse washer 13 has beenfractured, the floats 10 are moored at the hose body 2 by mooring ropes15 accommodated in cutout portions 21 of the float mounts 11a, 11b. Thismooring rope 15 is composed of a rope made of fiber or steel wire, thelength of which is not less than the depth of water in which the hose isused. It is necessary that the specific gravity of the float 10 is lowerthan that of fluid such as sea water or water so that the float 10 canrise to the surface, and the material of the float 10 is notparticularly limited. In order to enable the float to be easilyidentified when it has risen onto the surface of the sea or water, it ispreferable that the color of the float 10 is, for example, orange. Onefloat 10 may be attached to either of the float mounts 11a, 11b,however, it is preferable that a plurality of floats 10 are attached toboth float mounts 11a, 11b. Especially, as illustrated in FIG. 6, it ispreferable that the float 10 is formed to be annular and divided intothree or four pieces by the same angle and respectively attached to thefloat mount 11aor 11b. Of course, a plurality of pairs of connectingmembers such as the wires 12, fuse washers 13 and nuts 14 are providedin accordance with the number of the floats 10. When a plurality offloats 10 are provided as described above, even when either of the fusewashers 14 is not fractured, or even when either of the fuse washers 14is hooked so that the float 10 can not be separated from the hose body2, other floats 10 are separated and rise on the surface. In this way,some of the floats 10 attached to the hose body 2 can rise to thesurface.

Next, the action of the hose of the embodiment described above will beexplained as follows.

When the rubber tube layer 4 and the main pressure cord layer 5 of thehose body 2 are damaged and the fluid leaks out, the leaking fluid flowsinto the chamber 9 and stays there. Then, by the action of the fluid,the auxiliary pressure cord layer 7 is inflated. Therefore, the cords cof the cord ply being inclined with respect to the longitudinaldirection of the hose body 2 by the angle θ₂ are moved so that theinclination angle θ₂ can be reduced. In this embodiment, the helix angleθ₂ of the cords c of the auxiliary pressure cord layer 7 is relativelylarge. Therefore, a force is applied in a direction in which the angleθ₂ is reduced. Accordingly, the auxiliary pressure cord layer 7 iselongated in the longitudinal direction of the hose body 2, and thecover rubber layer 8 on the auxiliary pressure cord layer 7 is alsoelongated in the same manner.

Together with the elongation of the cover rubber layer 8 in thelongitudinal direction, the float mounts 11a, 11b are moved at both endsof the hose body 2. Therefore, the wire 12 is pulled in the direction ofarrow A shown in FIG. 5, so that a load is impressed upon the fusewasher 13. When the auxiliary pressure cord 7 is further elongated andthe length is increased to a predetermined value (a predetermined amountof deformation), the fuse washers 13 are fractured, and the floats 10are separated from the float mounts 11a, 11b, that is, the floats 10 areseparated from the hose body 2 and rise to the surface. Since the raisedfloats 10 are moored by the mooring ropes 15, they do not move away fromthe hose body 2, so that the raised floats 10 are floating near the hose1, the inner construction of which has been damaged. Consequently, whenthese floats 10 are discovered, damage to the inner construction of thehose installed in the sea or water can be easily detected. In thisconnection, in the first embodiment, it is possible to provide anappropriate amount of play to the wire 12 so that a certain amount ofelongation can be allowed to the hose body 2 until the fuse washer 13 isfractured while consideration is given to a relation between thepressure of fluid that has leaked out to the chamber 9 and theelongation (deformation) of the hose body 2.

In the first embodiment described above, when the fuse washer 13 isfractured, the float 10 is separated. However, instead of fracturing thefuse washer 13, it is possible to fracture both end portions of the wire12 of the connecting member.

FIGS. 7 and 8 are views showing the second embodiment of the presentinvention. Only the points different from the first embodiment will beexplained as follows. In this second embodiment, the hose body 2 isexpanded and deformed in the radial direction when the rubber tube layer4 and the main pressure cord layer 5 have been damaged and the fluid hasflown into the chamber 9. In the hose body 2 of the second embodiment,the helix angle θ₂ of the cords c of the cord plies in the auxiliarypressure cord layer 7 is determined to be in a range of 20°≦θ₂ ≦50° withrespect to the longitudinal direction of the hose body 2. The reason isas follows. When the angle θ₂ exceeds 50°, the hose 2 can not besufficiently expanded in the radial direction. On the other hand, whenthe angle θ₂ is smaller than 20°, the flexibility of the hose body 2 isdeteriorated. As described above, in the second embodiment, when theangle θ₂ is smaller than that of the first embodiment, the auxiliarypressure cord layer 7 is expanded and deformed mainly in the radialdirection by the pressure of leaking fluid.

As illustrated in FIGS. 7 and 8, the float 10a is disposed adjacent tothe annular float mount 11 integrally formed around the rubber coverlayer 8. Also, the float 10a is held onto the hose body 2 when theannular float fixtures 12a, engaged with the two grooves 10b formed inthe circumferential direction, are fastened by the bolt 16, fuse washer13 and nut 14. It is preferable that a plurality of floats 10a areprovided, and it is more preferable that the floats 10a are divided into3 or 4 pieces by an equal angle, because the float mounting work canthen be easily executed. In the same manner as the first embodiment, inorder to prevent the floats 10 from moving away from the hose body 2 inthe case where the fuse washer 13 has been fractured, each float 10a ismoored to the hose body 2 by the mooring rope 15 accommodated inside thefloat mount 11.

In the second embodiment, when the rubber tube layer 4 and the mainpressure cord layer 5 of the hose body 2 are damaged and the fluid leaksout, the leaking fluid flows into the chamber 9 and stays there. Then,by the action of the staying fluid, the auxiliary pressure cord layer 7is pushed. Therefore, the cords c of the cord ply, being inclined withrespect to the longitudinal direction of the hose body 2 by the angleθ₂, are moved so that the inclination angle θ₂ can be increased.Accordingly, the auxiliary pressure cord layer 7 is expanded anddeformed in the radial direction of the hose body 2, so that the coverrubber layer 8 on the auxiliary pressure cord layer 7 is also expandedwhen it is pushed by the auxiliary pressure cord layer 7.

Then, the float 10a and the float fixture 12a are also pushed in theradial direction, and a load not less than a predetermined value isapplied to the fuse washer 13. The fuse washer 13 is then fractured andthe float 10a is separated from the hose body 2 and rises to thesurface. Consequently, when the float 10a is discovered, moored to thehose 1, damage to the inner construction of the hose 1, installed in thesea or water, can be easily detected.

In the second embodiment described above, when the fuse washer 13 isfractured, the float 10a is separated, however, instead of the fractureof the fuse washer 13, it is possible to fracture an intermediateportion of the bolt 16 or to fracture the float fixture 12a.

FIGS. 9, 10, 11A and 11B are views showing the third embodiment of thepresent invention. Only the points different from those of the first andsecond embodiments will be explained as follows. In this thirdembodiment, in the case where the rubber tube layer 4 and the mainpressure cord layer 5 are damaged and the fluid flows into the chamber9, the hose body 2 is twisted. As illustrated in FIG. 10, in the hosebody 2 of the third embodiment, the auxiliary pressure cord layer 7 iscomposed of an asymmetrical cord layer. This asymmetrical cord layer iscomposed in the following manner:

The cords c in the cord layer are stacked in such a manner that thecords c are crossed to each other. The helix angles θ₃ and θ₄ of thecords c with respect to the longitudinal direction of the hose aredifferent according to the direction of inclination.

A preferable relation between the helix angles θ₃ and θ₄ is expressed asθ₃ <θ₄ <90°, and the angle θ₄ preferably expressed as 80°<θ₄ ≦90°. It ispreferable that the angle θ₃ is determined to be larger than the helixangle θ₁ (shown in FIG. 3) of the cords f of the main pressure cordlayer 5 so that the asymmetrical cord layer is not affected by thepressure of fluid flowing in the hose 1 before the main pressure cordlayer 5 is damaged. The angle θ₃ is determined so that it satisfies θ₁<θ₃ <θ₁ +20°, and preferably it satisfies θ₁ <θ₃ <60°. As describedabove, in the third embodiment, when the helix angle of the cords c ismade to be asymmetrical, the auxiliary pressure cord layer 7 is mainlysubjected to twisting deformation by the action of pressure of thefluid.

As illustrated in FIGS. 9, 11A and 11B, the float 10b is providedbetween a pair of annular float mounts 11c, 11d integrally formed on theouter circumference of the cover layer 8, through fuse bolts 17 whichare connecting members. It is preferable that a plurality of floats 10bare provided. It is more preferable that the floats 10b are divided into3 or 4 pieces by an equal angle. In order to prevent the floats 10b frommoving away from the hose body 2 when the fuse bolts 17 have beenfractured, each float 10b is moored to the hose body 2 by the mooringrope 15 accommodated inside the float mounts 11a, 11b.

In this third embodiment, when the rubber tube layer 4 and the mainpressure cord layer 5 of the hose body 2 are damaged and the fluid leaksout, the leaking fluid flows into the chamber 9 and stays there. Then,by the action of the fluid, the auxiliary pressure cord layer 7 ispushed. Since the helix angles θ₃ and θ₄ of the cords of the auxiliarypressure cord layer 7 disposed being inclined in the longitudinaldirection are different from each other according to the direction ofinclination, the hose body 2 is twisted in the longitudinal direction asillustrated in FIG. 12. Lines 18 used for visual recognition which areprovided on the hose body 2 in parallel with the longitudinal direction,are twisted as shown in FIG. 12. Accordingly, the float mount 11c istwisted in the direction of arrow a in FIG. 9, and the float mount 11dis twisted in the direction of arrow b in FIG. 9. When a load not lessthan a predetermined value is impressed upon the fuse bolt 17 due to thetwisting motion, the fuse bolt 17 is fractured, and the float 10b isseparated from the hose body 2 and raised on the surface. Consequently,when the float 10b is discovered moored to the hose 1, damage to theinner construction of the hose installed in the sea or water can beeasily detected.

It is possible to adopt the following construction: In the asymmetricalcord layer of the auxiliary pressure cord layer 7, the helix angles θ₃and θ₄ are made to be equal, and the cord layers of odd numbers arestacked so that the cords c are crossed to each other. Also, while thenumber of cord layers having the cords c inclined in one direction ismade to be different from the number of cord layers having the cords cinclined in the other direction so that they are crossed, the layers arestackedby an even number.

Also, the following construction may be adopted:

Asymmetrical cord layers of the auxiliary pressure cord layer 7 arestacked so that the cords c are crossed to each other, and the cordlayer has the cords c in which the product of the elastic modulus andthe sectional area is different. For example, steel cords and nyloncords are used, and the helix angles θ₃ and θ₄ are made to be equal. Dueto the foregoing, when the fluid has leaked out from the rubber tubelayer 4 and the main pressure cord layer 5, the auxiliary pressure cordlayer 7 can be twisted by the pressure of leaking fluid.

Also, the cord layers constructed in the manner described above may becombined, so that an asymmetrical cord layer may be formed. For example,the helix angles θ₃ and θ₄ may be made to be different, and the cords cmay be respectively made of steel and nylon cords.

Further, an arrangement of the cords c of the cord layer used for theaforementioned asymmetrical cord layer may be made to be symmetrical inthe transverse direction at the center of the longitudinal direction ofthe hose body 2. That is, as illustrated in FIG. 13, the cords c whichare inclined from the left to the upper right by the angle θ₅ arechanged to an arrangement in which the cords c are inclined from theleft to the lower right by the same angle θ₅, at the approximatelycentral portion M. In this way, the arrangement of the cords c is madeto be approximately symmetrical in the transverse direction. The abovecord layer can be obtained, for example, when the cords c disposed fromthe left to the upper right and the cords c disposed from the left tothe lower right are overlapped and wound at the central portion M whilean appropriate width is provided. When the aforementioned cord layersare stacked in the same manner as described above so that asymmetricalcord layers are formed, the twisting directions become opposite to eachother at the central portion M. Therefore, as illustrated by the visualrecognition lines 28 in FIG. 14, torque generated in twisting can becanceled. Therefore, the twisting torque is not transmitted to otherhoses to be connected. Further, the twist of the auxiliary pressure cordlayer 7 is not restricted by the objects on both ends to be connected.Accordingly, a good connecting condition, with respect to the objects tobe connected, can be maintained and, even when the hose is connected tothe objects, the twisting condition can be positively provided.

Embodiments of the present invention are explained above in detail.However, it should be understood that the invention is not intended tobe limited to the specific embodiments, and variations may be madewithout departing from the spirit and scope of the invention. Forexample, in the above embodiment, the number of layers (the number ofplies) of the main pressure cord layer 5 is larger than that of theauxiliary pressure cord layer 7, however, they may be the same.

The present invention is constructed in the manner described above. Whenthe main pressure cord layer is damaged and the transported fluid flowsinto the chamber and an amount of deformation of the auxiliary pressurecord layer is increased to a predetermined value, the connecting memberis fractured and the float is separated from the hose and raised on thesurface. When the float is sighted, the hose in which the main pressurecord layer has been damaged can be easily discovered.

Further, auxiliary apparatus such as a detector and a receiver are notrequired, and the hose can be easily installed, and further the cost canbe reduced. Unlike the detector, breakdown and malfunction are notlikely to occur in the apparatus of the invention. Accordingly, goodreliability can be maintained over a long period of time. Consequently,the present invention is suitable for use as the hose used for loading atanker with oil or the like, or for unloading the tanker.

We claim:
 1. A hose comprising: a main pressure cord layer for retaininga circulating fluid; an auxiliary pressure cord layer sheathing saidmain pressure cord layer; and a chamber for retaining the fluid leakingfrom said main pressure cord layer, said chamber being formed betweensaid main pressure cord layer and said auxiliary pressure cord layer,wherein said auxiliary pressure cord layer is capable of being deformedby the pressure of the fluid retained in said chamber, said hose furthercomprising a float moored at said hose, said float being connected tosaid hose through a connection member, wherein said connection member isfractured and said float is released from said hose when an amount ofdeformation of said auxiliary pressure cord layer has increased to apredetermined value.
 2. The hose according to claim 1, wherein anannular float mount is integrally attached to said hose, and a pluralityof floats divided into pieces in the circumferential direction aredisposed adjacent to said annular float mount.
 3. The hose according toclaim 2, wherein each float is attached to said hose with a mooring ropewhich is accommodated in said float mount.
 4. The hose according toclaim 1, wherein said auxiliary pressure cord layer is mainly deformedin the longitudinal direction of said hose by the action of pressure ofthe fluid retained in said chamber, a pair of float mounts areintegrally attached to said hose at an interval in the longitudinaldirection, said floats are respectively disposed on said float mounts,said floats are connected by wires penetrating through said floatmounts, and said floats are released from said hose when the amount oflongitudinal deformation of said auxiliary pressure cord layer hasincreased to a predetermined value.
 5. The hose according to claim 4,wherein said float is connected to said wire through a fuse washer whichis fractured when a predetermined stress is applied.
 6. The hoseaccording to claim 1, wherein said auxiliary pressure cord layer ismainly expanded and deformed in the radial direction of said hose by theaction of pressure retained in said chamber, said float mount isintegrally attached to said hose, said float, attached to and disposedadjacent to said float mount, is fastened and fixed to said hose by anannular float fastening fixture, and said float is released from saidhose when an amount of expanding deformation in the radial direction ofsaid auxiliary pressure cord layer has increased to a predeterminedvalue.
 7. The hose according to claim 6, wherein said annular floatfixture is fastened and fixed to said hose through a fuse washer to befractured by a predetermined stress and also through a bolt and nut. 8.The hose according to claim 1, wherein said auxiliary pressure cordlayer is mainly deformed in the twisting direction by the action ofpressure of the fluid retained in said chamber, a pair of float mountsare integrally attached to said hose at an interval in the longitudinaldirection, said floats are disposed between these float mounts, and saidfloats are respectively connected to the float mounts through fuse boltsto be fractured by a predetermined stress.
 9. The hose according toclaim 8, wherein said float is annular and divided into a plurality ofpieces in the circumferential direction, and the pieces of said dividedfloat are alternately connected to one and the other of the pair offloat mounts by said fuse bolts.